Ser. No. 09/695,107, Electromagnetic Driving Apparatus and Electromagnetic Relay, filed Oct. 25, 2000, now Pat. No. 6,426,689.
1. Field of Invention
The present invention relates to an electromagnet driving apparatus and an electromagnetic relay by the use of a permanent magnet.
2. Related Art
Conventionally, there was an electromagnet driving apparatus for use with a bistable electromagnetic relay that was constituted as shown in FIG. 31(a). In FIG. 31(a), there is constituted an 2a or 2b type electromagnetic relay, in which a U-shaped iron core 1 has a permanent magnet 2 vertically erected from the center of a central piece 1c in the iron core 1, an armature 3 has both end portions opposed to the pole faces for the pole pieces 1a, 1b defined by side pieces on both sides of the iron core 1, the armature 3 being freely movable in seesaw motion around the fulcrum of a projection 5 provided centrally on a lower face of the armature 3 on an upper end face of the permanent magnet 2, the armature 3 carrying the contact springs 4a, 4b with respective free ends extending in the direction toward both ends of said armature, the contact springs 4a, 4b having the moving contacts 6a, 6b on the lower face at their tip that are opposed to the fixed contacts 7a, 7b, in which a seesaw motion of the armature 3 enables one contact part to be turned on, and the other contact part to be turned off. In this case, an exciting coil is wounded centrally around the central piece 1c of the iron core 1, for example.
An operation state of the armature 3 is kept by the magnetic poles of the permanent magnet 2 even if an exciting current for the coil is turned off. In the reverse operation, the coil is excited in a direction of canceling a attraction force of the permanent magnet 2 on the adsorption side, and the armature 3 is reversely operated around the fulcrum of the armature 3 owing to a return force of a hinge spring and an attraction force acting on the opposite end portion of the armature 3, so that the contact in the on state is turned off, and the contact in the off state is turned on.
In this electromagnetic relay, the spring load (X) is symmetrical, the attraction force characteristic (I) with the permanent magnet 2 at the time of no excitation is also symmetrical, and operation attraction characteristic (II) and the reverse operation attraction force characteristic (III) are symmetrical, as shown in FIG. 31(b).
By the way, when the 2a(1a) type electromagnetic relay is constituted using the same electromagnet driving apparatus, a contact spring 4a is provided only on one side, as shown in 32A.
Accordingly, the spring load characteristic (X) is asymmetrical, as shown in FIG. 32(b). In this case, when an exciting current is passed through the coil to keep the on operation state, the operating voltage is increased, while in a self-holding mode with a magnetic force of the permanent magnet 2, the set voltage (for turning on the operation) is increased.
In order to solve a problem of FIGS. 32(a) and (b), if a coil 8 is wounded around a pole piece 1b on the side of a contact spring 4b, as shown in FIG. 33(a), an exciting attraction force on the side where the coil is wounded is increased, the width of attraction force being broadened with respect to the attraction force at the time of no excitation, but the attraction force characteristic at the time of no excitation remains symmetrical. Hence, there is the unsolved problem that it is difficult to be matched with the asymmetrical spring load.
FIG. 34 is an exploded perspective view of a 2a or 2b another balance armature conventional electromagnetic relay. In this conventional example, a case 117 is covered on an armature block B3 incorporated with a body block B2.
As shown in FIG. 35(a), the body block B2 is fabricated in such a way that a central piece of a U-shaped iron core 101 is contained into a coil bobbin 102 for winding a coil 103 by insert molding, a permanent magnet 104 is bridged between the pole pieces 101a, 101b on both sides of the iron core 101 to perform a coil block B1, this coil block B1 being incorporated in a predetermined region of a metallic hoop member formed with a coil terminal plate 105, a fixed terminal plate 107 with a fixed contact 106, and a common terminal plate 108 by punching, the coil terminal plate 105 being welded to a coil terminal 109 jutting out of the coil bobbin a body 110 consisting of a resin molding is formed by insert molding so as to bury partially the coil block B1, the common terminal plate 108, the fixed contact terminal plate 107 and the coil terminal plate 105, a terminal part of each terminal plate 108, 107, 105 being extended out of this body 110, a common terminal fixture 111 provided in the fixed contact 106 and the common terminal plate 108 being exposed as a block, and then the terminal parts are severed and separated from the metallic hoop member, each terminal part projecting on an upper end side of the body 110 being bent and arranged on a bottom face side of the body 110.
An armature block B3 comprises, as one block, an armature 112 made of a magnetic material, a molding 113 into which a central part of the armature 112 is inserted, a contact spring 115 with a moving contact 114, and a common spring 116 serving as a hinge spring formed integrally with this contact spring 115, the molding 113 having the contact spring 115 and the common spring 116 being inserted into the molding 113 and secured therein, as shown in FIG. 34.
By the way, in the conventional electromagnetic relay as described above, the entire coil block B1 was sealed and shaped with the resin molding 108 to form an insulating wall between the coil 103 and the fixed contact 106, and secure an insulation distance. Therefore, the manufacturing process was complex, and it was necessary to regulate or limit the temperature conditions such as the temperatures of the metal mold or the molding resin, the pressure conditions such as the molding injection pressure, and the molding conditions such as the limited injection position to prevent the molding resin from being applied to the coil at or near right angles when injecting the molding resin, thereby not to apply stress on the coil 103 at the time of molding, because the coil 103 is integrally molded.
This invention has been achieved in the light of the above respects, and it is an object of the invention to provide an electromagnet driving apparatus which is easily matched with the spring load characteristic even if used as a driver for the equipment with an asymmetrical spring load, wherein the width between an exciting attraction force and a non-exciting attraction force can be broadened by making the attraction forces at the time of excitation and no excitation asymmetrical, and an electromagnetic relay having a stable performance that can be easily matched with the asymmetrical spring load in constituting a 2a(1a) type relay.
Another object of the invention to provide an electromagnetic relay which can be easily produced without requiring the adjustments or limitations of the molding conditions, in which the basic size between a pole face of an iron core and a fixed contact can be attained at high precision.
To accomplish the above-mentioned problems, according to a first aspect of the present invention, there is provided an electromagnet driving apparatus comprising an iron core of substantial U-shape having the pole piece in parallel on both sides thereof, at least one coil wounded around said iron core, an armature freely movable in seesaw motion around a fulcrum provided between both ends of said armature, which are opposed to the pole faces at the top of the pole pieces on both sides of said iron core, and a permanent magnet for making up a closed magnetic circuit of any one end of said armature and said iron core via a pole face at the top of a pole piece of said iron core corresponding to said one end to attract one end of said armature to the corresponding pole face at the top of said pole piece of said iron core, in which said armature can be reversed by passing an exciting current through said coil in a direction canceling a magnetic force of said permanent magnet, provided that said permanent magnet and said fulcrum for said armature are provided at a position off the center between said pole piece on both sides of said iron core. As constituted in the above-described way, wherein the permanent magnet and the fulcrum of the armature are provided at an off-centered position between the pole pieces on both sides of the iron core. Therefore, there is the effect that the electromagnet driving apparatus with a greater width between the attraction force at the time of excitation and the attraction force at the time of no excitation can be realized by making the attraction force at the time of no excitation asymmetrical.
According to a second aspect of the invention, there is provided the electromagnet driving apparatus as defined in the first aspect of the present invention, wherein the permanent magnet having both ends magnetized to different magnetic poles is employed, with one end of the permanent magnet being placed on the lateral piece of the iron core to make the lengthwise direction of the permanent magnet parallel to the pole pieces of the iron core, and the fulcrum of the armature is placed at the other end. Therefore, there is the effect that the attraction force characteristic can be made asymmetrical more easily.
According to a third aspect of the present invention, there is provided the electromagnetic driver as defined in the first aspect of the present invention, wherein the permanent magnet having both ends magnetized to different magnetic poles is employed, with one end of the permanent magnet being placed on the lateral piece of the iron core at a position off the center between the pole pieces on both sides of the iron core to make the lengthwise direction of the permanent magnet parallel to the pole pieces of the iron core, and the fulcrum of the armature is placed on a line passing through the center between the pole pieces on both sides of the iron core. When used for the electromagnetic relay, the attraction force on the normally closed side can be increased without changing the attraction force on the normally open side, and the attraction force characteristic can be unbalanced. Therefore, there is the effect that the electromagnetic driver can be easily matched with the asymmetrical spring load.
According to a fourth aspect of the present invention, there is provided the electromagnetic driver as defined in the first aspect of the present invention, wherein the permanent magnet having both ends magnetized to different magnetic poles is employed, with one end of the permanent magnet being placed on the lateral piece of the iron core at a position off the center between the pole pieces on both sides of the iron core to make the lengthwise direction of the permanent magnet parallel to the pole pieces of the iron core, and the fulcrum of the armature is placed between the central position between the pole pieces on both sides of the iron core and an arranged position of the permanent magnet. When the electromagnetic driver is incorporated into the electromagnetic relay, the attraction force on the normally open side can be increased and the attraction force on the normally closed side reduced. Therefore, there is the effect that the electromagnetic driver can be easily matched with the asymmetrical spring load in the design of the simple type in particular (as current holding type, while flowing the current, it turned on the closed condition).
According to a fifth aspect of the present invention, there is provided the electromagnetic driver as defined in the first aspect of the present invention, wherein the permanent magnet having both ends magnetized to different magnetic poles is employed, with one end of the permanent magnet being placed on the lateral piece of the iron core at a position off the center between the pole pieces on both sides of the iron core to make the lengthwise direction of the permanent magnet parallel to the pole pieces of the iron core, and the fulcrum of the armature is placed between the pole piece of the iron core on a far side from an arranged position of the permanent magnet and the central position between the pole pieces on both sides. Therefore, there is the effect that the attraction force characteristic can be further unbalanced, and the electromagnetic driver can be easily matched with the asymmetrical spring load in the design of the simple type in particular.
According to a six aspect of the present invention, there is provided the electromagnetic driver as defined in the first aspect of the present invention, wherein the permanent magnet having both ends magnetized to different magnetic poles is employed, with one end of the permanent magnet being placed on the lateral piece of the iron core at a position off the center between the pole pieces on both sides of the iron core to make the lengthwise direction of the permanent magnet parallel to the pole pieces of the iron core, and the fulcrum of the armature is placed between an arranged position of the permanent magnet and the pole piece of the iron core on a near side to the arranged position. Therefore, there is the effect that the attraction force characteristic can be further unbalanced, and a large space for winding the coil can be secured.
According to seventh aspect of the present invention, there is provided the electromagnetic driver as defined in the first aspect of the present invention, wherein the permanent magnet having both ends magnetized to different magnetic poles is employed, with one end of the permanent magnet being placed on the lateral piece of the iron core corresponding to the center between the pole pieces on both sides of the iron core to make the lengthwise direction of the permanent magnet parallel to the pole pieces of the iron core, and the fulcrum of the armature is placed at a position shifted to the side of one pole piece off the central position between the pole pieces of the iron core. Therefore, there is the effect that the attraction force characteristic can be further unbalanced, while a large space for winding the coil can be effectively secured.
According to an eighth aspect of the present invention, there is provided the electromagnetic driver as defined in the first aspect of the present invention, wherein the permanent magnet having both ends magnetized to the same magnetic pole and an intermediate part off the center in the lengthwise direction to a different magnetic pole is employed, the permanent magnet is bridged to make both ends contact with the inner side faces at the tip of the pole pieces on both sides of the iron core. Therefore, there is the effect that the asymmetrical attraction force characteristic can be easily realized only by dislocating the magnetized position in the intermediate part of the permanent magnet.
According to a ninth aspect of the present invention, there is provided the electromagnetic driver as defined in the first aspect of the present invention, wherein the permanent magnet having both ends magnetized to the same magnetic pole and an intermediate part off the center in the lengthwise direction to a different magnetic pole is employed, the permanent magnet is bridged to make both ends contact with the inner side faces at the tip of the pole pieces on both sides of the iron core, and the fulcrum of the armature is placed at a corresponding position on a line passing through the center between the pole pieces on both sides of the iron core. When the electromagnetic driver is used for the electromagnetic relay, the attraction force on the normally closed side can be increased without changing the attraction force on the normally open side. Therefore, there is the effect that the attraction force characteristic can be unbalanced and the electromagnetic driver can be easily matched with the asymmetrical spring load.
According to a tenth aspect of the present invention, there is provided the electromagnetic driver as defined in the first aspect of the present invention, wherein the permanent magnet having both ends magnetized to the same magnetic pole and an intermediate part off the center to a different magnetic pole is employed, the permanent magnet is bridged to make both ends contact with the inner side faces at the tip of the pole pieces on both sides of the iron core, and the fulcrum of the armature is placed between the central position between the pole pieces on both sides of the iron core and the magnetized position in the intermediate part of the permanent magnet. When the electromagnetic driver is incorporated for the electromagnetic relay, the attraction force on the normally open side can be increased and the attraction force on the normally closed side can be reduced. Therefore, there is the effect that the electromagnetic driver can be easily matched with the asymmetrical spring load in the design of the simple type in particular.
According to an eleventh aspect of the present invention, there is provided the electromagnetic driver as defined in the first aspect of the present invention, wherein the permanent magnet having both ends magnetized to the same magnetic pole and an intermediate part of the center in the lengthwise direction to a different magnetic pole is employed, the permanent magnet is bridged to make both ends contact with the inner side faces at the tip of the pole pieces on both sides of the iron core, and the fulcrum of the armature is placed between the central position between the pole pieces on both sides of the iron core and the pole piece on a far side from the magnetized position in the intermediate part of the permanent magnet. Therefore, there is the effect that the attraction force characteristic can be further unbalanced, and the electromagnetic driver can be easily matched with the asymmetrical spring load in the design of the simple type in particular.
According to a twelfth aspect of the present invention, there is provided the electromagnetic driver as defined in the first aspect of the present invention, wherein the permanent magnet having both ends magnetized to the same magnetic pole and an intermediate part off the center in the lengthwise direction to a different magnetic pole is employed, the permanent magnet is bridged to make both ends contact with the inner side faces at the tip of the pole pieces on both sides of the iron corner and the fulcrum of the armature is placed between the magnetized position in the intermediate part of the permanent magnet and the pole piece of the iron core on a near side to the magnetized position. Therefore, there is the effect that the attraction force characteristic can be unbalanced without worrying about the space for winding the coil.
According to a thirteenth aspect of the present invention, there is provided the electromagnetic driver as defined in the first aspect of the present invention, wherein the permanent magnet having both ends magnetized to the same magnetic pole and a central part in the lengthwise direction to a different magnetic pole is employed, the permanent magnet is bridged to make both ends contact with the inner side faces at the tip of the pole pieces on both sides of the iron core, and the fulcrum of the armature is placed at a position shifted to the side of one pole piece off the central position between the pole pieces on both sides of the iron core. Therefore, there is the effect that the attraction force characteristic can be unbalanced without worrying about the space for winding the coil.
According to a fourteenth aspect of the present invention, there is provided the electromagnetic driver as defined in the first aspect of the present invention, wherein the permanent magnet is attached integrally in parallel to the armature, and is not disposed on the side of the iron core, so that the space occupied by the coil wounded around the iron core can be increased. Therefore, there is the effect that the number of turns of the coil can be increased.
According to a fifteenth aspect of the present invention, there is provided the electromagnetic driver as defined in the first aspect of the present invention, wherein the permanent magnet is attached to the armature so that the central position of the permanent magnet is shifted off a line passing through the center between the pole pieces on both sides of the iron core, and the fulcrum of the armature is placed on a line passing through the center between the pole pieces on both sides of the iron core. When the electromagnetic driver is used for the electromagnetic relay, the attraction force on the normally closed side can be increased without changing the attraction force on the normally open side. Therefore, there is the effect that the attraction force characteristic can be unbalanced, and the electromagnetic driver can be easily matched with the asymmetrical spring load.
According to a sixteenth aspect of the present invention, there is provided the electromagnetic driver as defined in the first aspect of the present invention, wherein the permanent magnet is attached to the armature so that the central position of the permanent magnet is shifted off a line passing through the center between the pole pieces on both sides of the iron core, and the fulcrum of the armature is placed at a shifted position between a line passing through the center between the pole pieces on both sides of the iron core and the central position of the permanent magnet. When the electromagnetic driver is incorporated into the electromagnetic relay, the attraction force on the normally open side can be increased and the attraction force on the normally closed side can be reduced. Therefore, there is the effect that the electromagnetic driver can be easily matched with the asymmetrical spring load.
According to a seventeenth aspect of the present invention, there is provided the electromagnetic driver as defined in fourteenth aspect of the present invention, wherein the permanent magnet is attached to the armature so that the central position of the permanent magnet is shifted off a line passing through the center between the pole pieces on both sides of the iron core, and the fulcrum of the armature is placed between the pole piece of the iron core on a far side from the central position of the permanent magnet and the central position between the pole pieces. Therefore, there is the effect that the attraction force characteristic can be further unbalanced, and the electromagnetic driver can be easily matched with the asymmetrical spring load.
According to an eighteenth aspect of the present invention, there is provided the electromagnetic driver as defined in fourteenth aspect of the present invention, wherein the permanent magnet is attached to the armature so that the central position of the permanent magnet is shifted off a line passing through the center between the pole pieces on both sides of the iron core, and the fulcrum of the armature is placed at a corresponding position between the central position of the permanent magnet and the pole piece of the iron core on a near side to the central position of the permanent magnet. Therefore, there is the effect that the attraction force characteristic can be unbalanced without worrying about the space for winding the coil.
According to a nineteenth aspect of the present invention, there is provided the electromagnetic driver as defined in fourteenth aspect of the present invention, wherein the permanent magnet is attached to the armature so that the magnetized position at the center of the permanent magnet is located on a line passing through the center between the pole pieces on both sides of the iron core, and the fulcrum of the armature is placed at a position shifted to the side of one pole piece of the iron core. Therefore, there is the effect that the attraction force characteristic can be unbalanced without worrying about the space for winding the coil.
According to a twentieth aspect of the present invention, there is provided the electromagnetic driver as defined in any one of first to sixth, eighth to eighteenth aspects of the present invention, wherein only one coil is provided. Therefore, there is the effect that the asymmetrical attraction force in an excited state can be secured.
According to a twenty-first aspect of the present invention, there is provided the electromagnetic driver as defined in the twentieth aspect of the present invention, wherein the coil is wounded around the iron core from the position at which the fulcrum of the armature is shifted to the position including the pole piece present in a central direction. Therefore, there is the effect that the width of the attraction force on the side where the coil is wounded can be increased.
According to a twenty-second aspect of the present invention, there is provided the electromagnetic driver as defined in any one of first to nineteenth aspects of the present invention, wherein the coil is wounded around the iron core from the position at which the fulcrum of the armature is shifted to the position including the pole pieces on both sides. Therefore, there is the effect that the width of the attraction force on both sides of the fulcrum can be increased.
According to a twenty-third aspect of the present invention, there is provided an electromagnetic relay comprising an electromagnet block having an iron core of substantial U-shape having the pole piece in parallel on both sides thereof, at least one coil wounded around said iron core, an armature freely movable in seesaw motion around a fulcrum provided between both ends of said armature, which are opposed to the pole faces at the top of the pole pieces on both sides of said iron core, and a permanent magnet for making up a closed magnetic circuit of any one end of said armature and said iron core via a pole face at the top of a pole piece of said iron core corresponding to said one end to attract one end of said armature to the corresponding pole face at the top of said pole piece of said iron core, said electromagnet block being disposed on a body, in which said armature has a contact spring extending in parallel to said armature with one end being attached to said armature, a moving contact at the other end of said contact spring extending in an end direction of said armature being opposed to a fixed contact on said body, said contact spring enabling said moving contact to be touched on or left away from said fixed contact in accordance with the seesaw motion of said armature, said armature being able to be reversed by passing an exciting current through said coil in a direction canceling a magnetic force of said permanent magnet, wherein said armature and the fulcrum for said permanent magnet are provided at a position off the center between said pole pieces on both sides of said iron core, shifted in an opposite direction to the end direction of said contact spring. As constituted in the above way, wherein the permanent magnet and the fulcrum of the armature are provided at a position shifted in an opposite direction to the end direction of the contact spring off the center between the pole pieces on both sides of the iron core. Therefore, there is the effect that the electromagnetic relay can be realized in which the asymmetrical attraction force can be provided, and the electromagnetic relay can be easily matched with the asymmetrical spring load having the contact spring on one side.
According to a twenty-fourth aspect of the present invention, there is provided the electromagnetic relay as defined in the twenty-third aspect of the present invention, wherein the permanent magnet having both ends magnetized to different magnetic poles is employed, with one end of the permanent magnet being placed on the lateral piece of the iron core to make the lengthwise direction of the permanent magnet parallel to the pole pieces of the iron core, and the fulcrum of the armature is placed at the other end. Therefore, there is the effect that the asymmetrical attraction force characteristic can be provided easily.
According to a twenty-fifth aspect of the present invention, there is provided the electromagnetic relay as defined in the twenty-third aspect of the present invention, wherein the permanent magnet having both ends magnetized to different magnetic poles is employed, with one end of the permanent magnet being placed at a position off the center between the pole pieces on both sides of the iron core to make the lengthwise direction of the permanent magnet parallel to the pole pieces of the iron core, and the fulcrum of the armature is placed on a line passing through the center between the pole pieces. Therefore, there is the effect that the asymmetrical attraction force characteristic can be provided easily.
According to a twenty-sixth aspect of the present invention, there is provided the electromagnetic relay as defined in the twenty-third aspect of the present invention, wherein the permanent magnet is attached integrally in parallel to the armature, and is not disposed on the side of the iron core, so that the space occupied by the coil wounded around the iron core can be increased. Therefore, there is the effect that the number of turns of the coil can be increased.
According to a twenty-seventh aspect of the present invention, there is provided the electromagnetic relay as defined in any one of twenty-third to twenty-sixth aspects, wherein only one coil is provided. Therefore, there is the effect that the asymmetrical attraction force characteristic in an excited state can be secured.
According to a twenty-eighth aspect of the present invention, here is provided the electromagnetic relay as defined in any one of twenty-third to twenty-sixth aspects, wherein the coil is wounded around the iron core from the position at which the fulcrum of the armature is shifted to the position including the pole piece present in a central direction. Therefore, there is the effect that the attraction force characteristic can be secured so that the electromagnetic relay can be easily matched with the asymmetrical spring load.
According to a twenty-ninth aspect of the present invention, there is provided the electromagnetic relay as defined in any one of twenty-third to twenty-sixth aspects, wherein the coil is wounded around the iron core from the position at which the fulcrum of the armature is shifted to the position including the pole pieces on both sides. The width of the attraction force on both sides of the fulcrum can be increased. Therefore, there is the effect that the attraction force characteristic can be secured so that the electromagnetic relay can be easily matched with the asymmetrical spring load.
According to thirtieth aspect of the present invention, there is provided the electromagnetic relay as defined in any one of twenty-third to twenty-ninth aspects, wherein a hinge spring has one end secured to the armature in an opposite direction to the other end direction of the contact spring, the other end being secured on the body. The space for arranging the hinge spring is secured and utilized by making use of the dead space. Therefore, there is the effect that the small electromagnetic relay can be produced.
According to a thirty-first aspect of the present invention, there is provided the electromagnetic relay as defined in the thirtieth aspect of the present invention, wherein the hinge spring is substantially U-shaped, at least the plate face on both side pieces being in the same direction as the plate face of the contact spring, the tip of one side piece being secured to the armature, the other side piece being disposed laterally and in parallel to the armature to allow its tip to be secured on the body. Therefore, there is the effect that the spring can be adjusted by shifting the central piece.
According to a thirty-second aspect of the present invention, there is provided the electromagnetic relay as defined in thirty-first aspect of the present invention, wherein the central piece of the hinge spring is bent to make its plate face perpendicular to the plate face of both side pieces. The spring adjustment can be made by picking up and shifting the central piece from above by means of an adjuster. Therefore, there is the effect that the spring adjustment can be easily made.
According to thirty-third aspect of the present invention, there is provided the electromagnetic relay as defined in any one of thirtieth to thirty-second aspect of the present invention, wherein the position at which the hinge spring is secured on the body is near the fulcrum position of the armature, where the perturbation of the fulcrum portion can be reduced. Therefore, there is the effect that the stable operation can be obtained.
According to thirty-fourth aspect of the present invention, there is provided an electromagnetic relay comprising an iron core of an electromagnetic drive mechanism for driving an armature and a contact terminal having a fixed contact that is touched on or separated from a moving contact of a contact spring that is movable by the operation of the armature, the iron core and the contact terminal being secured to a body made of a resin molding by integral molding to constitute a body block along with the body. Hence, the reference size between a pole face of the iron core and the fixed contact can be determined by the precision of a metal mold, and thus can be provided at high precision. In particular, a coil block that is fragile is not provided integrally in the body block by insert molding. Therefore, there is the effect that it is unnecessary to regulate or limit the molding conditions, including the molding temperatures such as the temperature of the metal mold or the temperature of the molding resin, the pressures such as the molding injection pressure, and the limited injection position to prevent the molding resin from being applied to the coil at or near right angles.
According to the thirty-fifth aspect of the present invention, there is provided the electromagnetic relay as defined in the thirty-fourth aspect of the present invention, wherein the iron core is the punched iron core, the cast iron core or the sintered iron core. In this case, a higher precision is attained in the bent portion (corner portion) than the bent iron core, and there is no need of providing a slide core for modifying the bending on the structure of the metal mold. Therefore, there is the effect that a number of body blocks can be molded at a time.
According to the thirty-sixth aspect of the present invention, there is provided the electromagnetic relay as defined in the thirty-fourth to thirty-fifth aspects of the present invention, wherein the iron core has a substantial U-shape, the pole pieces on both sides are secured to the body by integral molding to be exposed from the body, a permanent magnet is disposed between the pole pieces on both sides to make the lengthwise direction parallel to the pole pieces, a fulcrum of the armature being laid on the top of this permanent magnet to be freely movable in seesaw motion, a closed magnetic path is constituted by any one end of the armature and the iron core via a pole face at the top of a pole piece of the iron core corresponding to this one end, in which while one end of the armature is sucked onto the corresponding pole face at the top of the pole piece of the iron core due to a magnetic force of the permanent magnet, the armature can be reversed by passing an exciting current through the coil wounded around the iron core in a direction of canceling the magnetic force of the permanent magnet. Therefore, there is the effect that the electromagnetic relay of seesaw type can be produced.
According to a thirty-seventh aspect of the present invention, there is provided the electromagnetic relay as defined in the thirty-sixth aspect of the present invention, wherein the permanent magnet is secured onto the body by integral molding. In this case, a step of incorporating the permanent magnet into the body block can be omitted, and the basic size between the pole face and the fixed contact as well as the basic size between the pole faces of the permanent magnet can be obtained at high precision. As a result, there is the effect that the armature can be stabilized in stroke.
According to a thirty-eighth aspect of the present invention, there is provided the electromagnetic relay as defined in the thirty-sixth and thirty-seventh aspect of the present invention, wherein the coil is wound around the outer periphery of a barrel portion of the coil bobbin that is laid on the body with the pole piece passed through the central through hole, constituting a coil block along with the coil bobbin, the coil bobbin being accommodated within an insulating case to cover the coil, the insulating case being like a box with an opening at the bottom, and having, on a ceiling plane, an opening window through which the top portion of the pole piece passing through the central through hole of the coil bobbin is extended outside. In this case, the insulating distance between the coil and the other metal parts can be secured. Therefore, there is the effect that the electromagnetic relay can be miniaturized with the improved dielectric strength, and the insulating case can provide a mechanical protection for the coil during the transportation or handling of parts.
According to a thirty-ninth aspect of the present invention, there is provided the electromagnetic relay as defined in the thirty-eighth aspect of the present invention, wherein a resilient projecting piece having an engagement bore is integrally formed at least on the lower edge of each of a pair of opposed side walls for the insulating case, the engagement bore being internally engaged by an engaging projection formed on either side face of a collar portion for the coil bobbin located on the side of the body, when the insulating case is attached on the coil block. Therefore, there is the effect that the insulating case can be attached onto the coil bobbin by one touch.
According to claim fortieth aspect of the present invention, there is provided the electromagnetic relay as defined in any one of thirty-eighth and thirty-ninth aspect of the present invention, wherein a rib is provided to surround an opening of the central through hole through which the top portion of the pole piece extends, except for a region to which an end portion of the armature is faced, the rib higher than the top position of the pole piece being extended from the collar portion on the upper side of the coil bobbin, and the rib, along with the top portion of the pole piece, being extended through an opening window of the insulating case outward. In this case, a large insulation distance between the pole pieces of the iron core and the coil can be secured. And the wear powder on the pole faces of the pole pieces can be prevented from scattering, when the wear powder is produced during the opening or closing operation, and the consumed powder arising at the contact portion in the opening or closing operation can be prevented from being moved to the pole faces. Therefore, there is the effect that the stable operation can be obtained over time.
According to a forty-first aspect of the present invention, there is provided the electromagnetic relay as defined in any one of thirty-eighth to fortieth aspects, wherein a coil terminal is protruded on either side face of the collar portion in the coil bobbin to be laid on the body, the coil terminal having a top portion passed through the body and exposed to the bottom face side of the body, when the coil bobbin is laid on the body, an end portion of the collar portion being fitted within a notch formed on an upright wall stood on the outer edge of the body, and grasped between a projection on an inner wall face of the case attached on the body and the body, when the coil bobbin is laid on the body. Therefore, there is the effect that the coil bobbin can be stably secured by making use of a wall thickness of the end portion of the collar portion to extend the coil terminal for which a predetermined wall thickness is required.
According to a forty-second aspect of the present invention, there is provided the electromagnetic driving apparatus as defined in the eight aspect of the present invention, wherein the fulcrum of the armature is placed corresponding to a magnetized position in the intermediate part of the permanent magnet. Therefore, there is the effect that the asymmetrical attraction force characteristic can be easily realized only by dislocating the magnetized position in the intermediate part of the permanent magnet.